The present invention relates to the hydrolysis of metal halides and more particularly to the production of the corresponding metal oxides by the hydrolysis of the chloride and calcining the hydrolysis product.
Current practice for the production of Nb.sub.2 O.sub.5 and TaCl.sub.5 utilizes for example, NbCl.sub.5 from a ferroniobium (FeNb) chlorinator as the feed for Nb.sub.2 O.sub.5 production. The NbCl.sub.5 is mixed with H.sub.2 O forming a hydrolysed NbOCl.sub.3.xH.sub.2 O in a highly acidified (HCl) solution. This solution is pH adjusted with ammonia to further convert the NbOCl.sub.3.xH.sub.2 O to hydrolysed Nb.sub.2 O.sub.5. The solution is then filtered and calcined at high temperature to produce dry Nb.sub.2 O.sub.5. The addition of ammonia is expensive and produces a waste disposal problem. Further, the addition or loading of NbCl.sub.5 to water is limited in the present practice to about 2 lbs of NbCl.sub.5 per gallon of water. The filtration of the ammoniated NbCl.sub.5 water mixture is required to eliminate excess water and decrease the mass of material going to the kiln which typically would then contain only 15% to 20% solids. Finally the prior use of ammonia produced ammonium chloride in the off gases from the kiln which required a large flue gas scrubbing capacity.
It is therefore an object of the present invention to eliminate the use of ammonia in the production of Nb.sub.2 O.sub.5 by the hydrolysis of NbCl.sub.5.
It is a further object of the present invention to increase the production of Nb.sub.2 O.sub.5 while decreasing the volume of water required.
It is also an object of the present invention to provide a more energy efficient process for the production of Nb.sub.2 O.sub.5.